During Phase I, IA Inc. and HRL developed a novel, regenerable, fiber optic biosensor for monitoring in real-time, molecular interactions between estrogen receptor modulators and both hER-alpha and hER-beta. These biosensors don't require fluorophore labeling of receptor, are more specific than sensors monitoring mass on the sensor surface, and utilize only 10 femtomoles of receptor per sample. Sensors provide a kinetic association and dissociation curve for a compound in 9-10 minutes. Sensor data on the interaction between a variety of xeno-, phyto- and endogenous estrogens and hER-alpha or hER-beta generally agrees with previously reported binding studies. Exciting new data was also obtained. Of particular significance is the observation that genistein, a phytoestrogen believed to be protective against certain cancers, produces a greater increase in stable complex formation between ERE and hER-beta than it does with hER-alpha. Also diethyl phthalate, a compound widely used in colognes and cosmetics, selectively activates formation of stable complex between ERE and hER-alpha but not hER-beta. Phase II work will develop a prototype instrument and further explore the possibility of distinguishing between beneficial and harmful estrogen receptor modulators by kinetic measurements using hER-alpha and hER-beta. PROPOSED COMMERCIAL APPLICATION: Not Available